Split-Gate MOSFET Trench Design for Void-Free Dielectric
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing split-gate MOSFETs face challenges in maintaining high breakdown voltage and low on-resistance due to voids in the dielectric layer between conductors, which affect mechanical strength and electrical performance.
Innovation Solution
A manufacturing method for split-gate MOSFETs involving the formation of trenches with varying diameters and dielectric layers to prevent void formation, where the first trench has a larger inner diameter than the second trench, allowing for expanded process windows and improved material filling without affecting device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deep trench split gate is added to improve breakdown voltage and balance electric field, then breakdown voltage is improved, but the trench has a small critical dimension causing voids in the dielectric layer which worsens manufacturing precision and reliability
Solution Approach 1:
The patent divides the single trench structure into two separate trenches (first trench and second trench) that are respectively formed. This segmentation allows each trench to have optimized dimensions, specifically making the first trench wider than the second trench, thereby avoiding the small critical dimension problem while still achieving the split-gate effect for improved breakdown voltage
Solution Approach 2:
The patent applies different trench width specifications to different parts of the structure. The first trench has a larger inner diameter (first width) while the second trench has a smaller inner diameter (second width). This local differentiation allows the first trench to provide sufficient space for void-free dielectric layer formation, while the second trench maintains the necessary split-gate functionality
2Adaptability or versatility
If the trench critical dimension is reduced to achieve split-gate structure, then device functionality is improved, but voids are generated in the dielectric layer which worsens mechanical strength and electrical performance
Solution Approach 1:
By segmenting the trench structure into two separate trenches with different width requirements, the patent enables the first trench to be sufficiently wide for robust dielectric layer formation (improving mechanical strength), while the second trench provides the necessary split-gate configuration for enhanced device functionality
Solution Approach 2:
The patent assigns different dimensional characteristics to different regions: the first trench is designed with larger dimensions to provide mechanical strength and void-free dielectric formation, while the second trench is designed with smaller dimensions to achieve the split-gate effect, thereby simultaneously improving both strength and functionality
3Adaptability or versatility
If the trench critical dimension is reduced to achieve split-gate structure, then device functionality is improved, but the risk of leakage is increased
Solution Approach 1:
The patent segments the trench structure into two separate trenches, allowing the first trench to be formed with sufficient width to accommodate a complete, void-free dielectric layer. This ensures proper electrical isolation and reduces leakage risk, while the second trench maintains the split-gate configuration for improved device functionality
4Ease of manufacture
If a uniform trench structure is used, then manufacturing is simpler, but it is difficult to achieve both high breakdown voltage and low on-resistance simultaneously
Solution Approach 1:
The patent applies different width specifications to different trenches: the first trench has a larger inner diameter optimized for dielectric layer formation, while the second trench has a smaller inner diameter optimized for split-gate functionality. This local differentiation enables simultaneous achievement of high breakdown voltage and low on-resistance, while the overall manufacturing process remains relatively simple
Solution Approach 2:
By dividing the trench structure into two separate trenches with different dimensional optimizations, the patent enables each trench to fulfill specific functions that collectively achieve both high breakdown voltage and low on-resistance, while maintaining manufacturing simplicity through the use of standard semiconductor fabrication processes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively prevents voids in the dielectric layer, enhancing the mechanical and electrical performance of the device while maintaining high breakdown voltage and low on-resistance.
Implementation Method 1
an oxidation process is performed to convert the portion, which is located on the sidewall of the cavity, of the semiconductor layer into an oxide layer
Data Source
AI summary
Disclosed is a split-gate MOSFET and a manufacturing method, comprising: forming a cavity in a semiconductor layer; form a first trench based on the cavity; forming a second trench communicated with the first trench and extending in a same direction with the second trench; forming a first dielectric layer and a second dielectric layer; forming a first conductor located in the second trench and isolated from the semiconductor layer by the first dielectric layer; forming a third dielectric layer covering a surface of the first conductor; forming a second conductor located in the first trench, isolated from the semiconductor layer by the second dielectric layer, and isolated from the second conductor by the third dielectric layer; forming a body region adjacent to the first trench, wherein an inner diameter of the first trench is larger than an inner diameter of the second trench. The manufacturing method expands a process window.